An example of an induction heating device for heating a rolling element bearing is disclosed in EP2728965. The device includes at least two induction coils, plus first and second temperature sensors for measuring the temperature of the bearing inner and outer rings respectively. The device is configured to adjust the power combination supplied to the induction coils if a maximum temperature difference between the bearing rings is exceeded.
Induction heating is also widely applied in cooking appliances. An example of a device comprising a heating plate with at least two concentric induction coils, each supplied by a separate generator, is disclosed in U.S. Pat. No. 5,808,280. The device includes a controller which is configured to cause the generators to operate according to a sequential order, starting with the generator that supplies the innermost coil and progressing to the outermost coil that is covered by a cooking receptacle, based on a detection step in which the presence of a load on each induction coil is determined. The determination is made as a function of the current passing through the induction coil in question. The device further includes a thermal probe for measuring the temperature of the cooking receptacle, which measurement can be used by the controller to adjust the heating cycle.
There is still room for improvement.